Binary mixtures of protonated and perdeuterated 1,4-polybutadiene have been examined by small-angle neutron scattering and are shown to exhibit an upper critical solution temperature. The scattering results above the critical temperature are described by the mean-field theory of de Gennes for homogeneous binary polymer mixtures. These results contradict the universally held assumption that mixtures of deuterated and protonated polymers of otherwise identical chemical structure form ideal solutions.

• Received 1 July 1985

DOI:https://doi.org/10.1103/PhysRevLett.55.2425